Description, Causes and Risk Factors:
Cardiomegaly is an enlarged heart. In most cases, enlargement of the heart occurs over an extended period of time, due to an injury to the heart or any other medical condition. The heart responds to the injury/condition by re-modeling itself in a way that lets it continue to do its job of pumping blood. This sometimes results in a stretching of the heart muscle.
Hypertrophic - Just as our skeletal muscles hypertrophy (grow in size) in response to increased demand, cardiac muscle undergoes hypertrophy when placed under a high workload for a prolonged period of time. Some cardiac hypertrophy is normal and reversible, such as that seen in athletes and pregnant women. Pathologic hypertrophy is the result of diseases that place increased demand on the heart, such as chronic hypertension, myocardial infarction, and valvular damage. Left ventricular hypertrophy (LVH) is the most common type of hypertrophic heart disease. A common cause of LVH is chronic hypertension, which increases the afterload on the left ventricle. This means the left ventricle has to increase contractility and/or preload to maintain the same stroke volume. Over time the added stress on the left ventricular myocardium results in muscle hypertrophy and re-modeling of the left ventricle to a less efficient size and shape. This leads to a diminishing ejection fraction (EF), meaning the heart must work even harder to maintain cardiac output. The larger heart also demands more blood flow, and so becomes more susceptible to ischemic injury.
Dilative - The heart can become enlarged due to dilation of the myocardium. An example is dilated cardiomyopathy (DCM), which is the most common form of non-ischemic cardiomyopathy. In DCM, the heart becomes weakened and enlarged, and congestive heart failure (CHF) quickly follows. Signs and symptoms are those of left and/or right heart failure, and signs on autopsy would include central hemorrhagic necrosis in the liver.
There are many causes of Cardiomegaly. It is a compensation mechanism by the heart to try to push more blood with each contraction to make up for elevated blood pressure, increased demand due to failing lungs, leaky valves in the heart or aorta (large main artery),congenital (genetic) reasons, or diabetes. Cardiomegaly can even occur due to athletic training to become more efficient to feed the muscular tissue. The reason the heart gets into trouble if the enlargement goes too far is that the heart muscle fibers stretch out so much that they cannot get a good tug on each other to form an efficient contraction. At this point the output of blood pumped by the heart per stroke actually begins to reduce.
The most common cause is elevated blood pressure. Diabetes is also a great inducer of this. Uncontrolled blood sugars cause the arteries and arterioles to thicken so less blood can get through and cause a back-up of pressure. Also high levels of sodium in your diet.
Coronary artery disease and heart attacks.
In many cases, no cause can be identified, which is called Idiopathic cardiomegaly.
High blood pressure that is inadequately treated for a long time.
The damage in many cases is ir-reversable and it is cumulative. Each time there is damage done, there is less heart function that remains for the rest of your life and that usually translates to a much shorter life. An enlarged heart that continues to be damaged will end up in Congestive Heart Failure (CHF) and usually kidney failure soon follows.
Cardiomegaly is not a condition in itself, but a symptom of an underlying problem that is causing the heart to work harder than normal.
Symptoms may include:
Shortness of breath [SOB].
Cardiomegalyis diagnosed using a number of tests including:
Chest x-ray - this allows the cardiologist to see the overall shape and size of the heart and lungs.Cardiomegaly is often detected on an anteroposterior chest x-ray (AP CXR). and it involves measuring the distance from the midline of the spine to the most lateral aspect of the cardiac apex, and adding this distance to that found from the same midline to the most lateral aspect of the right atrium. This number is then divided by the largest horizontal width of the chest, from right to left pleural surface. This value is known as the cardiothoracic ratio (CTR). A CTR > 0.5 indicates cardiomegaly.
Echocardiogram - sound waves sent to a special machine present a picture of the beating heart, so the doctor can see the heart as its chambers contract and relax.
Doppler study - shows blood flow through the heart valves and evaluates whether the valves are functioning normally.
Electrocardiogram - measures electrical activity in the heart and can assess heart rhythm and evidence of old infarction or ischemia.
Medical history - including a complete Physical examination.
Treatment depends on the underlying cause but options can include:
Regular cardiovascular exercise.
Adopting a low-fat diet.
Dietary adjustments to reduce blood cholesterol levels.
Frequent medical check-ups to make sure the treatments are working.
Addressing the underlying problem (for example through diet, stopping smoking, exercise and medication to help control high blood pressure.
Other Treatment Options:
Implantable cardioverter-defibrillator (ICD). A device implanted in the chest can electrically restart the heart if it stops beating. Some devices can also stimulate the heart to pump more effectively.
Heart replacement: In very few people with Cardiomegaly and severe congestive heart failure, Heart transplant may be recommended.
Surgery or a less invasive procedure can sometimes repair or replace a damaged heart valve causing Cardiomegaly.
NOTE: The above information is educational purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.
DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.
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